I just got a replacement barrel and made the mistake of looking at it with a borescope.

Tell me what you think of this.

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Too much brightness, not enough contrast.

Yes sir.  My question is would that amount of uneven throat bother you?  Pretend that it's a $750 barrel and you've spent the money to have the action trued and are putting it in a chassis.

On one side the throat is deeper than the groove and on the other it barely touches the land.

High side /low side

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How does it shoot ?

No idea,  this is the replacement for the one that wouldn't come close to the 1/2moa guarantee after $200 worth of ammo.  It should of been attached to my rifle which I'd shipped to them.

That'd look good for a $200 5.56 AR barrel. Rather crap for a custom tube.

.30 cal?

7mm

That's why I have the borrowed borescope.  I've been troubleshooting 3 $200 ar barrels. None are cut this crooked.  

If the barrel was spinning it would of been an equal ring around the chamber.   So the reamer was spinning and ran into a stationary barrel off bore.

ETA,  Machinist buddy said that it didn't get indicated in right.

If you look through my videos, I have uploaded a good sample of different barrels. I don't pretend to have any idea what predicts performance, but it's nice to learn maybe what to look for as you go.

https://www.youtube.com/watch?v=JQ10gS_kWfg

My opinion as well.

Your machinist buddy could be right.

It could also be that the reamer holder wasn’t up to the task.

I'll check them out.  They did tell me that they cleaned it up with a new reamer before putting it on my rifle.

No one spins the reamer. They did not have the barrel running true.

Machinist buddy is right.

<This.

1/2 moa guarantee is impossible. Whoever said they can meet that standard is blowing smoke up your ass.

1 moa guarantee is borderline possible, with hand loads.

A lot of this falls on you. I have been an active competitor and chronic accuracy pursuer for over 40 years. Any rifle that routinely groups under 1 moa is a keeper!

I have a lot of firearms with premium barrels and none of them are .5 moa rifles, even using custom hand loaded match ammo. I might shoot a .5 moa group, or very close to that, on occasion. Guaranteeing that level of performance is outright impossible.

This barrel ended up being inconsistent and not accurate. Anytime I found a load that looked promising on a range trip I'd load up more of that recipe and others to test and it would "like" something else the next trip. Tried clean barrel, dirty barrel,  muzzle brakes, suppressor,  different scopes,  multiple powder and bullet combinations.  You never knew how it was shoot trip to trip besides 1.5" to 3".

The company finally got back to me and are working to do another barrel. I borescoped this one and the throat is firecracked after 200 rounds of slow fire.

It's not that I expect half moa 100% of the time but a consistent sub moa with premium components in handloads is required for the $725 price tag.

A 6.5 proof on a savage has ruined my expectations.  It's a half moa rifle. As in half inch is the worse group it shoots handloads, normally smaller . I have a $189 6.5 ba barrel in a dpms that's .75moa gun.


Here was a good day for the barrel.  Don't let the good groups fool you. The next trip they'd be a train wreck.  
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Hows the brass look ? If your gunsmith cut that throat crooked the opening would have to be cut oversized also . Maybe mic the fired brass and a sized piece near the belt to see if its stretched oversized .

I told them about it when I sent the barrel to them because it was suppose to be installed on my rifle before it shipped and the "smith" used something to recut the throat area. You could clearly see it in the borescope and it left a figure 8 shaped soot pattern on the neck.  Had more split necks with this barrel as well.  

I would measure the brass but it doesn't matter now since it's going back to them next week.

This is all that matters.

It’s not a beauty contest.

I absolutely agree with this. I’ve got lots of distinguished badges, trophies, medals, plaques, etc.

I’ve got a lot of expensive rifles, but I don’t have a lot of 0.5 moa rifles. Anything under an moa is special. Half or less is truly exceptional.

Those groups are good. Different components might achieve your goal. A better brake or recoil management might be the ticket. Or, maybe that’s the best it can do. It’s tough to say.

I missed them re cutting the throat that wouldn't change the body at all but its real easy to screw up the throat .  
Everyone can make a mistake I've made a few the important part is making it right .

They cleaned up the throat because the chamber is off center of the bore.

Those groups are not "good" for the price of this barrel let alone close to their guarantee.  If you picked the best group on that target and ran that load again it wouldn't group the same.  If the bullet isn't contacting the throat centered to the bore it's going to wear one side more than the other causing accuracy issues. It may stabilize at some point and be consistent for a short time but who knows. Its basically banking the rounds into the rifling.

I'm one year, 400 rounds and two barrels into this project. Wanna take a guess at how much 400 rounds of 280ai costs?

Just to update and close it out.
Sent the rifle back with a couple boxes of ammo to the barrel maker. Their smith did a great job of going through the rifle and went so far as to aquire dies and components to reload to find a acceptable load. He also found that the precision ground lug I got from them with the barrel didnt seat all the way in my chassis and replaced it.  I'm very happy with the work done and the communication from the smith.  The new barrel looks great in the borescope.

I'm 100 rounds into load development and have a few loads that are good enough for now that I can take on an upcoming hunt.  Have a 162eldx going 3030fps that's given me multiple sub half inch 3 shot groups with 5 rounds in the 1/2 to 5/8 range.  It seems to like the rounds loaded long.  This barrel is picky on what muzzle device is on it.  It doesn't care for a thread protector either.  I found a single port suppressor adapter that it tolerates well though.

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Nice to hear the shop made it right.  

I would not have been happy with an off center chamber or throat either.  

I have had crowns that didn’t impress me but the guns shot well. One was a factory M700V that had a tool mark dragging out of the crown.  It was sub moa out of the box which was a big deal in the ignites so I quickly changed my mind not to have a remington fix it.   The other was a custom .308 that was shooting decently.  My smith was at the range and looked at the crown.  It was a little rough/ fast cut.  He said bring it back to the shop that wasn’t a perfect finish cut.  He recut it it and the groups got a little tighter.

What? What kind of rifles and handloads are you shooting? I shoot a custom tikka t3x and a Desert Tech SRS a1. Both are sub .5 with handloads and the DTI is capable of shooting zeros occasionally. I've shot hornady and FGMM 6.5 cm, 308, and 300 NM. If I don't shoot .5 or less I get annoyed.

ETA pics because I know the "show us pics" is coming. Most of these are 3 rd groups I shot during load workup.
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Total encompassing cone of fire of a given rifle/ammo combination is extremely unlikely to be under 0.5 MOA.  Under 1 MOA sure, under .75 MOA, yes there are some of those out there.  Under 0.5 MOA are very few and far between.  As soon as you add a human shooter to the equation it happens even less often.

If your rifle AVERAGES 0.5 MOA for a 5 shot group, an all-encompassing cone of fire is going to be closer to .8-1.1 MOA.  What you will find with 3 shot, 5 shot, hell even 10 shot groups is that the MPOI will walk around group to group.  With 3's and 5's it's especially bad and you can almost expect .1-.4 MOA shift in MPOI from group to group.  When you run 30+ shots-- either all in one sitting or as a composite group with a common reference aiming point-- you stop seeing that POI shift, and you stop seeing variation from group to group.

For example, shoot 20x 5-shot groups and you'll get groups that are .15 MOA and you'll get groups that are .70 MOA, and everything in between.  Shoot 20x 50 shot groups and you will produce 20x 0.85-0.90 MOA groups.  There's even a rabbit hole to explore regarding using group size as a metric.  Regardless of if I shoot 3 rounds or 3000 rounds, I'm only measuring the worst 2 shots, with zero regard to the dispersion pattern of the others.  Mean radius is a dramatically better metric, and there are several other methods beyond that to better define the dispersion profile.  All of it is better than simple group size.

At the end of the day, the all-encompassing cone of fire is a good tool for calling effective range, and to go a step beyond that the full dispersion profile (mean radius +) is an even better tool for conducting hit probability calculations that don't involve blowing smoke up your own ass.  If you think you have a 1/2 MOA rifle, then in an indoor (fixed environmental conditions) range, you should never miss a 1/2 MOA target provided your sighting system is aligned properly.  In reality you will miss a 1/2 MOA target an impressive percent of your shots.

Unfortunately the cost associated with ammo, barrels, and the problem of dwindling barrel life-- and good old "Tradition"-- have all lead this industry into accepting "testing methods" that are exceedingly skimpy on the statistical significance front.

Standard load testing for groups requires ten round groups. Three round groups reveal nothing. Five round groups can begin to show promise.

I have a lot of rifles, even a factory Colt H-bar that will group ten rounds under an inch at 100. I don't own a single rifle that will group ten rounds under a half inch consistently at 100 yards. On rare occasions I can flirt with half moa, but usually I'm a little over that standard. 5/8" is what I usually can accomplish with my best rifle/ammo combination.

Virtually all competitive venues have a minimum 10 rounds per stage, slow fire events are normally 20 rounds, plus sighters.

Shooting three rounds to test group size tells me absolutely nothing.